When it comes to home lighting, one question I receive often is how many lights can be on a 15 amp circuit breaker.
The number of fixtures that can be on a 15-amp circuit depends on the wattage of the bulbs, and the lighting load should not exceed 80% of the breaker rating.
If you plan to add more bulbs to your circuits, make sure it is within the safe level to avoid overloading the breaker.
How to calculate the number of light fixtures that can be on a 15 amp circuit breaker.
In order to get a specific number of lights to be on a 15 amp circuit, you must follow the NEC 80% breaker rating rule.
The law states that you should not continuously load electrical circuits more than 80% of their maximum rated capacity.
So to get the number of light fixtures to put on a 15 A breaker, apply the NEC rule by multiplying 15 amp with 80% or 0.8.
That is 15 amps x 0.8 = 12 amps.
Then you convert the amperage to watts. If the line voltage is 120v, you convert it to watts by multiplying 12 amps with 120 volts.
12 A X120 V = 1440watts.
If you are to put 100-watt incandescent lights on a 15 amp breaker, it can safely accommodate 14 bulbs.
that is 1140w / 100w = 14.4 or 14 bulbs.
Calculating the number of fluorescent or incandescent bulbs to put on a 15 amp breaker
If you are to calculate the number of bulbs to be on a single circuit be it fluorescent or incandescent, all you have to do is to divide 1440w with the wattage of the light bulb.
Example: How many 200 w incandescent bulbs can be on one 15-amp circuit breaker?
The maximum number of 200 w bulbs to be on the circuit will be 1440 watts divided by 200 w = 7 bulbs.
You can also use the same step to get the number of fluorescent bulbs.
Calculating the number of led or recessed lights to be on a 15-amp circuit
LED bulbs use less energy to produce bright lumen. A 10 watts led bulb can produce a light strength equivalent to 100 w traditional bulb.
If you are to calculate the number 10 w led bulb to be on the 15A circuit, the result will be 1440 / 10 = 144 led bulbs.
Though you cannot install all these light bulbs at home, you can see how much energy you can save by replacing incandescent lighting with LED bulbs.
Effects of installing too many lights on a circuit
Installing too many lights and outlets on a single circuit leads to severe electrical hazards such as
Overheating: When too much current flows through a circuit, the wires and components become very hot. This can melt wire insulators, leading to short circuits and electrical fires.
Frequent tripping of the breaker: Circuit breakers are designed to protect the circuits from overloads. So each time they detect excessive currents, they trip the breaker.
Damage to electrical appliances
When too many lights or appliances are on one circuit, they may cause electrical surge and damage to electrical devices.
Increase in electricity bill
Overloaded circuits often draw more power than required thereby increasing the energy bills.
Conclusion
From this article, you can see that it is simple to figure out how many lights you can run on a 15 A circuit.
However, you should be careful while converting amps to watts to avoid mistakes.
Should in case you are in doubt about the conversion, contact a qualified electrician to help you.
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